Hydraulic disc clutch

ABSTRACT

A fixed annular hydraulic cylinder slidably receives an annular piston of a special, generally Z-shaped cross-section, which pilots at one of its parallel legs on a horizontal shoulder portion of the cylinder. The other piston leg serves as a positioning pilot surface for an annular needle bearing transmitting axial thrust to a pressure plate of a disc clutch stack. A large projected annular are of the piston is engaged by the needle bearing for high torque capacity, and a large diameter radial and axial thrust-sustaining ball bearing journals a driver hub of the clutch within the latter&#39;&#39;s cylinder portion, at the axial side of the piston opposite the needle bearing.

United States Patent 1 3,684,069 Pray [451 Aug. 15, 1972 [54] HYDRAULICDISC CLUTCH 130,830 2/1951 Sweden.................192/85 CA [72]Inventor: Lawrence H. Pray, 35296 Malibu,

Sterling Heights, Mich. 48077 Primary Examiner-Benjamin W. WycheAttorney-Whittemore, Hulbert & Belknap [22] Filed: Oct. 22, 1970 211App]. No.: 82,944 [57] ABSIRACT A fixed annular hydraulic cylinderslldably receives an annular piston of a special, generally Z-shapedcross- [52] U.S. CI ..192/85 CA, 92/158, 192/110 B Section, which pilotsat one f its parallel legs on a Int. horizontal shoulder portion of thecylinder The other Field 192/35 91 13 A piston leg serves as apositioning pilot surface for an annular needle bearing transmittingaxial thrust to a [56] References Cited pressure plate of a disc clutchstack. A large projected annular are of the piston is engaged by theneedle UNITED STATES PATENTS bearing for high torque capacity, and alarge diameter 3,444,971 5/1969 Davidson ..l92/85 CA and axial lwfnals adnver hub of the clutch within the latter 5 cylinder 3,429,410 2/1969Hansen 192/85 CA portion, at the axial side of the piston opposlte theFOREIGN PATENTS OR APPLICATIONS needle s- 213,l65 1/196] Austria..192/85 CA 3Claims,2DrawingFigures PATENTEDwc 15 :912

INVENTOR LAWRENCE H. ZQAY ATTO NEYS HYDRAULIC DISC CLUTCHCROSS-REFERENCE TO RELATED APPLICATION My co-pending applications, Ser.No. 825,567, filed May 19, 1969, now abandoned, and continuationapplication Serial No. 82,1 15 show and describe a hydraulic clutchgenerally comparable in structure and function to the present clutch.

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention hasapplication in the fluid-pressure operated fixed cylinder type clutchfield,in particular in torque transmission installations in which greatload bearing capacity and length of life can be offered in a clutch ofvery compact form.

2. Description of the Prior Art Hansen US. Pat. No. 3,011,608 of Dec. 5,I961, discloses a generally similar type of hydraulic unit. Hansen US.Pat. No. 3,429,4 l of Feb. 25, 1969 and Davidson US. Pat. No. 3,444,971of May 20, I969 also relate to hydraulically operated disc clutchesemploying an axial thrust needle bearing, but in each case therelationship of bearing, cylinder and piston features differs materiallyfrom what is herein shown.

SUMMARY OF THE INVENTION The improved clutch incorporates an annularhydraulically powered, rotatively and axially fixed cylinder having anannular, axially acting piston therein which releasably compresses astack of clutch discs to drivingly couple an output member with aco-axial input member hub. The input hub is journalled for rota tion inthe cylinder structure through the agency of a large size radial andaxial thrust sustaining ball bearing; and clutch engaging axial thrustis exerted by the piston on the clutch disc stack through the agency ofa large diameter needle bearing spaced radially well outwardly of adriving hub representing the power input member. Moreover, the pistonprojects a large annular radial area subject to the hydraulic actuatingpressure for high torque capacity.

The circular radial zone of the needle bearing unit substantiallycoincides with a corresponding circular zone of overlap of alternatediscs of the friction disc stack; and the needle bearing is preciselypositioned in this radial zone by having its inner diameter pilotedpositively on an adjacent cylindrical shoulder formation of the powerpiston. Thus a very strong axial clutch-engaging thrust may betransmitted to the disc stack in a very stable distributed manner.

The piston has means for the hydraulic power liquid lubrication of theneedle bearing; and an improved Z- shaped cross sectional outline of thepiston not only provides the pilot shoulder surface for the needlebearing, but also enables the cylinder to afford a large space for thereception of the large diameter ball bearing.

Thus a clutch of given prescribed diameter limit may incorporate thelargest possible ball bearing, for increased bearing life. This alsopermits the use of maximum size hub bores for improved shaft stiffnessand rigidity.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary view in sectionin a plane including the axis of the clutch; and

FIG. 2 is a fragmentary view in transverse section on broken line 2-2 ofFIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT The clutch 10 of the invention,comprises an input or driving hub 11 which is internally keyed at 12 tobe rotatively operated by an appropriate drive shaft (not shown). Thishub is rotatably joumalled by a very rugged radial and axial thrustsustaining ball bearing 13, the inner race of which, as it rotates withhub l 1, bearing against an axial restraining snap ring-type abutment 14seated in hub 11. The outer race of bearing 13 is fixedly received in alarge diameter annular recess 15 of rectangular cross-section, whichrecess is formed in and opens outwardly of one axial side of a fixedhydraulic power cylinder part 16 of clutch 10. This part is suitablyrestrained in any desired manner against rotation; the cylinder thusserving as a stable radial bearing support for the driver hub 11.Cylinder member 16 has a radial boss provided with a hydraulic pressureliquid intake port 17, and is formed on its side opposite hearing 13 toprovide an annular cylinder space 18 of special shape intermediate itsradial limits.

The space 18 is communicated with the intake port 17 by an axialpressure passage 19 in part 16 which is of generous bore size. the space18 being in part defined by cylindrical, radially spaced and coaxialouter and inner walls 20, 21, respectively integral with the cylinderpart. These slidably guide an annular power piston 22, also of specialcross section, and annular packings 23 and 24 on the piston respectivelyseal the latter in relation to the parallel cylinder walls 20 and 21.

As indicated above, the piston 22 is of generally Z- shapedcross-section, characterized by parallel, radially outer and innercylindrical leg portions 25, 26 on which the respective packings 23, 24are carried, and an integral connecting body portion 27 of considerableradial length. This lies adjacent and parallel to a radially extendingcylinder wall 28 of equal length, which connects the inner axialcylinder wall 21 with the portion of cylinder part 16 in which thepressure inlet port 17 and passage 19 are formed.

The radially outer axial leg at of piston pilots slidably on cylinderpart 16 atop the latters radial wall 28,and carries an axially extendingpin 29 which is received with good clearance, and for a substantialaxial depth, in the cylinder inlet passage 19. Pin 29 thus prevents anundue possible rotation of piston 22 in the fixed cylinder space, yetleaves ample passage space for the pressure liquid.

It is seen that the Z-shaped contouring of piston 22 and the cylinderwalls radially within the latter afiords a large volume in space l5 toreceive the ball bearing 13, enabling the latter to be selected in amaximum size consistent with the overall 0.d. limitation on the clutchl0, hence guaranteeing a long bearing life under substantial load, alsogreat shaft rigidity.

The radially inner axial leg 26 presents an outer cylindrical surface 30on which a needle bearing 32 is piloted at its inner diameter, thusinsuring a precisely maintained location of this bearing in relation topiston 22 and the remainder of the clutch structure.

A left-hand race 33 (FIG. I) of bearing 32 abuts the radial cylinderwall 28, which has a small through opening 34 for admission to theneedle bearing of hydraulic pressure fluid from the cylinder space tolubricate bearing 32. The right-hand race 35 abuts to the right anannular pressure plate 36 of a clutch disc stack, generally designated38, the race 35 being piloted on a small cylindrical shoulder on plate36 coinciding axially with the bearing pilot shoulder 30 on piston 22.

It is seen by reference to FIG. 1 that the radial wall 28 of the pistonpresents, in addition to the portion of its leg 25 directly exposed topressure passage 19, a large annular radial area on its left which isalso subject to fluid pressure actuation; and this endows the clutchwith a high torque capacity. lt is also seen that the piston shoulder 30pilots the needle bearing 32 in an annular pressure zone which has alarge radial spacing from the axis of the clutch.

In addition to its annular pressure plate 36, the clutch stack 38comprises an axially spaced backing plate 39 rearwardly abutting asnap-type restraining ring 40 on drive hub 11, both of the plates 36, 39having radially inner spline formations 41 keying the same for rotationwith the hub. Alternate, radially inner friction discs 42 of the stack38 also have spline connections to the hub. A radially outer set offriction discs 43 alternate with the discs, 42 being drivinglysplineconnected by cars 44 at their outer periphery (FIG. 2) to anannular, cup-like output or driven member 45, the ears 44 taking intoaxially extending openings 46 defined between fingers 47 of member 45. Aseries of Belleville springs 48 are alternately positioned betweenpressure plate 36, clutch discs 42, 43 and backing plate 39 of the stack38, operating in a known manner to spread these members relative to oneanother when the clutch 10 is in non-clutching condition, i.e., whenpiston 22 is not subject to hydraulic pressure.

As in the case of my co-pending application identified above, theconsiderable radial size of needle bearing 32 enables its circularcenter median zone to be brought into axial coincidence with anapproximate common radial circular center line or common annular medianzone of the piston 22, the pressure plate 36, the projected area ofoverlap of friction discs 42, 43 and the backing plate 39. These zonesalso align axially with a large area annular pressure actuated radialwall zone of the piston 20, hence heavy axial forces involved in thecompacting of the disc stack 38 are stably borne and transmitted.

What is claimed is:

l. A fluid pressure operated clutch, comprising a fixed cylinder partproviding a pressure space defined in part by parallel, radially spacedaxial wall portions connected by a radial wall portion, from whichradial portion the axial portions extend in opposite directions, apiston slidable in said pressure space, said piston having radiallyspaced axial portions extending in opposite axial directions, whichpiston portions are connected by a radial portion, being slidablyengaged with said respective axial wall portions of the cylinderpressure space, a clutch unit releasably compressible axially by saidpiston under fluid pressure in said space, an annular bearingtransmitting compressive force between said piston and clutch unit, saidbearing being axially piloted on one of said axial piston portions andaxially abutting said radial piston portion, and another annular bearingdisposed in a space of said cylinder part on the axial side of saidradial wall portion of the cylinder pa t opposite e piston, saidcylinder part having an axial y extending pressure passage to saidpressure space located radially outwardly of said other bearing and thespace receiving the latter, said first named bearing being a needlebearing and said other bearing being a ball bearing, the radiallyoutermost of said axial piston portions having a pin element extendingaxially into said pressure passage of said cylinder part to opposerotation of the piston relative to said part.

2. The clutch of claim 1, in which said clutch unit comprises axiallyalternating annular members radially overlapped in an annular radialzone common to said needle bearing and said radial portions of thepiston and cylinder part.

3. The clutch of claim 1, in which said radial portion of said pistonhas a passage located radially inwardly of said pin element andcommunicating said pressure space with a space occupied by said needlebearing.

8 I t I! III UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3,684,069 Dated August 15, 1972 Invencofls) Lawrence H. PrayIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Show assignment of Letters Patent from Inventor to Formsprag Company, ofWarren, Michigan.

Signed and sealed this 13th day of March 1973.

(SEAL) Attest:

ROBERT GOTTSCHALK .FLETCHER JR EDWARD M Commissioner of PatentsAttesting Officer FORM PO-1050 (10- USCOMM-DC scan-ps9 9 US GOVERNMENTFRINTlNG OFFICE 199 O366334

1. A fluid pressure operated clutch, comprising a fixed cylinder partproviding a pressure space defined in part by parallel, radially spacedaxial wall portions connected by a radial wall portion, from whichradial portion the axial portions extend in opposite directions, apiston slidable in said pressure space, said piston having radiallyspaced axial portions extending in opposite axial directions, whichpiston portions are connected by a radial portion, being slidablyengaged with said respective axial wall portions of the cylinderpressure space, a clutch unit releasably compressible axially by saidpiston under fluid pressure in said space, an annular bearingtransmitting compressive force between said piston and clutch unit, saidbearing being axially piloted on one of said axial piston portions andaxially abutting said radial piston portion, and another annular bearingdisposed in a space of said cylinder part on the axial side of saidradial wall portion of the cylinder part opposite the piston, saidcylinder part having an axially extending pressure passage to saidpressure space located radially outwardly of said other bearing and thespace receiving the latter, said first named bearing being a needlebearing and said other bearing being a ball bearing, the radiallyoutermost of said axial piston portions having a pin element extendingaxially into said pressure passage of said cylinder part to opposerotation of the piston relative to said part.
 2. The clutch of claim 1,in which said clutch unit comprises axially alternating annular membersradially overlapped in an annular radial zone common to said needlebearing and said radial portions of the piston and cylinder part.
 3. Theclutch of claim 1, in which said radial portion of said piston has apassage located radially inwardly of said pin element and communicatingsaid Pressure space with a space occupied by said needle bearing.